1. Field of the Invention
The present invention is generally related to the field of oil and gas production equipment, and, more particularly, to a Christmas tree with an internally positioned flowmeter.
2. Description of the Related Art
In oil and gas wells, the produced fluid is often a combination of gas, oil and water. Production of oil and gas from a well normally involves the use of a series of inlet and outlet cutoff valves commonly referred to as a Christmas tree that is positioned above the wellhead. It is very important to be able to accurately meter the amount of oil and gas flowing from such wells. Multi-phase flowmeters have been developed that are able to measure the flow of each of the three phases—oil, gas and water—in a single production stream. However, such multi-phase flowmeters are typically less accurate when the volume percentage of gas, sometimes referred to as the “gas cut,” is too high, e.g., greater than 97% or so. One known solution to such a problem involves separating some of the gas from the production stream to thereby reduce the gas cut. The separated gas flow is then measured by a separate gas meter, while the remaining production stream is measured using a multi-phase flowmeter. After the measuring step is performed, the two split streams are again combined downstream of the meters for transportation to a storage or production facility. In such a situation, the production stream from the well is separated only for metering purposes.
In multiple well situations, separate metering of the type just described is typically accomplished in one of two ways. One method involves routing the production flow from all of the wells to a single manifold. Thereafter, the combined flow from the manifold is then separated and metered as described above. This technique does not permit measurement of the production flow from each well independently.
Another method involves the use of an independent gas separator and metering unit which can be moved from well to well. Using this technique, the production flow from a particular well is temporarily re-routed through the gas separator/metering unit to measure the flow. While this technique enables the production flow of each well to be independently monitored, the flow from multiple wells cannot be monitored independently at the same time. Moreover, this latter technique involves repeated relocation of the gas separator/metering unit from well to well.
The present invention is directed to an apparatus and methods for solving, or at least reducing the effects of, some or all of the aforementioned problems.